Magnetic head having a damascene-fabricated write coil structure with coil layers extending between the poles for reduced electrical resistance

ABSTRACT

Magnetic heads having write coil structures with reduced electrical resistances for reducing thermal protrusion are disclosed. In one illustrative example, a magnetic head includes a magnetic yoke; a write gap layer formed between upper and lower poles of the magnetic yoke; and a write coil having a plurality of coil layers. Each coil layer of the write coil extends continuously between the upper and the lower poles through a plane defined by the write gap layer. Preferably, the write coil is formed using a damascene process, such that each coil layer is wider than each coil separating layer. Such a structure provides for a relatively large amount of coil materials to be used, which reduces the coil&#39;s electrical resistance. This, in turn, reduces the heat generated by the write coils during operation. Further, either one or both of the lower and upper poles may include a horizontally laminated structure of alternating magnetic and non-magnetic dielectric layers to further reduce heating caused by eddy current losses. Since thermal protrusion is reduced, the fly height of magnetic head may be made relatively small with a reduced risk of head-to-disk crashes and disk scratches.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to ApplicationSer. No. 10/629,060 having a filing date of Jul. 29, 2003, now U.S. Pat.No. 7,079,353 issued on Jul. 18, 2006, which is hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to magnetic heads in disk drives, andmore particularly to magnetic write heads having write coil structureswith relatively low electrical resistances to reduce thermal protrusion.

2. Description of the Related Art

A write head is typically combined with a magnetoresistive (MR) or giantmagnetoresistive (GMR) read head to form a magnetic recording head,certain elements of which are exposed at an air bearing surface (ABS).The write head comprises first and second pole pieces connected at aback gap that is recessed from the ABS. The first and second pole piecesterminate at the ABS where they define first and second pole tips,respectively. An insulation stack, which comprises a plurality ofinsulation layers, is sandwiched between the first and second polepieces, and a coil layer is embedded in the insulation stack. Aprocessing circuit is connected to the coil layer for conducting writecurrent through the coil layer which, in turn, induces magnetic writefields in the first and second pole pieces. A non-magnetic gap layer issandwiched between the first and second pole tips. Write fields of thefirst and second pole tips at the ABS “fringe” across the gap layer. Ina magnetic disk drive, a magnetic disk is rotated adjacent to, and ashort distance (fly height) from, the ABS so that the write fieldsmagnetize the disk along circular tracks. The written circular tracksthen contain information in the form of magnetized segments with fieldsdetectable by the MR or GMR read head.

An MR read head includes an MR sensor sandwiched between first andsecond non-magnetic gap layers, and located at the ABS. The first andsecond gap layers and the MR sensor are sandwiched between first andsecond shield layers. In a merged MR head, the second shield layer andthe first pole piece are a common layer. The MR sensor detects magneticfields from the circular tracks of the rotating disk by a change inresistance that corresponds to the strength of the fields. A sensecurrent is conducted through the MR sensor, where changes in resistancecause voltage changes that are received by the processing circuitry asreadback signals.

A GMR read head includes a GMR sensor which manifests the GMR effect. Inthe GMR sensor, the resistance of the MR sensing layer varies as afunction of the spin-dependent transmission of the conduction electronsbetween magnetic layers separated by a non-magnetic layer (spacer) andthe accompanying spin-dependent scattering which takes place at theinterface of the magnetic and non-magnetic layers and within themagnetic layers. GMR sensors using only two layers of ferromagneticmaterial (e.g., nickel-iron, cobalt, or nickel-iron-cobalt) separated bya layer of nonmagnetic material (e.g., copper) are generally referred toas spin valve (SV) sensors manifesting the SV effect. Recorded data canbe read from a magnetic medium because the external magnetic field fromthe recorded magnetic medium (the signal field) causes a change indirection of magnetization in the free layer, which in turn causes achange in resistance of the SV sensor and a corresponding change in thesensed current or voltage. A GMR head is typically associated with adesign in which the second shield layer and first pole piece are not acommon layer. These pieces are separated by a non-magnetic material,such as alumina, or a metal that can be deposited using physical vapordeposition, RF sputtering, or electroplating techniques, for example.

One or more heads may be employed in a magnetic disk drive for readingand writing information on circular tracks of a rotating disk. Amagnetic recording head is mounted on a slider that is carried on asuspension. The suspension is mounted to an actuator which places themagnetic head to locations corresponding to desired tracks. As the diskrotates, an air layer (an “air bearing”) is generated between therotating disk and an air bearing surface (ABS) of the slider. A force ofthe air bearing against the air bearing surface is opposed by anopposite loading force of the suspension, causing the magnetic head tobe suspended a slight distance (i.e. its fly height) from the surface ofthe disk. Fly heights are typically around 5–20 nanometers (nm) intoday's disk drives.

It is generally desirable to minimize the fly height of a magnetic head.If the fly height is too large, it could adversely affect theperformance of the read and write head. Unfortunately, any protrusion ofmetal layers at the ABS will make these layers dangerously close to thedisk, especially in disk drives with low fly heights. This could resultin head-to-disk crashes or disk scratches.

“Temperature-induced protrusion” (T-PTR) refers generally to thephenomenon where magnetic head materials physically and outwardlyprotrude from the ABS at elevated temperatures due to the differences inthe coefficients of thermal expansion of the various layers which formthe head. “Write-induced protrusion” (W-PTR) refers to protrusion due toheating of the magnetic head during the writing process. There are twocontributors to W-PTR: (1) Joule heating produced in the write headcoils; and (2) yoke core losses. Joule heating and yoke core losses areboth induced with AC write current. W-PTR is dominated by thetemperature gradient in the head structure, with the highest temperatureregions being near the write coils and the yoke, and substrate materialat ambient temperature.

Accordingly, what is needed is an improved magnetic head that provides areduced thermal protrusion so that head-to-disk crashes and/or diskscratches can be avoided.

SUMMARY

Magnetic heads having write coil structures with reduced electricalresistances for reducing thermal protrusion are described herein. In oneillustrative embodiment, a magnetic head includes a magnetic yoke; awrite gap layer formed between upper and lower poles of the magneticyoke; and a write coil having a plurality of coil layers. Each coillayer extends continuously between the upper and the lower poles througha plane defined by the write gap layer. Preferably, the write coil isformed using a damascene process, such that each coil layer isrelatively wider than each coil separating layer.

Such a structure provides for a relatively large amount of coilmaterials to be used which reduces the coil's electrical resistance.This, in turn, reduces the heat generated by the write coil duringoperation. Further, either one or both of the lower and upper poles mayinclude a horizontally laminated structure of alternating magnetic andnon-magnetic dielectric layers to further reduce heating caused by eddycurrent losses.

Advantageously, a magnetic head with a reduced thermal protrusion isprovided. Accordingly, the fly height of the magnetic head may be maderelatively small with a reduced danger of head-to-disk crashes and diskscratches.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, as well as the preferred mode of use, reference should bemade to the following detailed description read in conjunction with theaccompanying drawings:

FIG. 1 is a planar view of an exemplary magnetic disk drive;

FIG. 2 is an end view of a slider with a magnetic head of the disk driveas seen in plane II—II;

FIG. 3 is an elevation view of the magnetic disk drive wherein multipledisks and magnetic heads are employed;

FIG. 4 is an isometric illustration of an exemplary suspension systemfor supporting the slider and magnetic head;

FIG. 5 is a partial elevation view of the slider and magnetic head asseen in plane V—V of FIG. 2, where the magnetic head includes amagnetoresistive (MR) read sensor and a non-pedestal type write head;

FIG. 6 is a top view of the second pole piece and coil layer, a portionof which is shown in FIG. 5, with all insulation material removed;

FIG. 7 is a partial ABS view of the slider taken along plane VII—VII ofFIG. 5 to show the read and write elements of the magnetic head;

FIG. 8 is a partial elevation view of the slider and magnetic head asseen in plane V—V of FIG. 2, where the magnetic head includes an MR orgiant magnetoresistive (GMR) read sensor and a pedestal-type write head;

FIG. 9 is a partial ABS view of the slider taken along plane IX—IX ofFIG. 8 to show the read and write elements of the magnetic head of FIG.8;

FIG. 10 is a partial elevation view of the slider and magnetic head incross-section, wherein the magnetic head has a write coil structure ofthe present invention;

FIG. 11 is the structure shown and described in relation to FIG. 10,except that an upper pole piece of the magnetic yoke is made ofalternating layers of magnetic and non-magnetic dielectric material;

FIG. 12 is the structure shown and described in relation to FIG. 11,except that a lower pole piece of the magnetic yoke is also made ofalternating layers of magnetic and non-magnetic dielectric material;

FIG. 13 is a partial elevation view of the slider and magnetic head incross-section, wherein the magnetic head has another write coilstructure of the present invention;

FIG. 14 is the structure shown and described in relation to FIG. 13except that an upper pole piece of the magnetic yoke is made ofalternating layers of magnetic and non-magnetic dielectric material; and

FIG. 15 is the structure shown and described in relation to FIG. 14,except that a lower pole piece of the magnetic yoke is also made ofalternating layers of magnetic and non-magnetic dielectric material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is the best embodiment presently contemplatedfor carrying out the present invention. This description is made for thepurpose of illustrating the general principles of the present inventionand is not meant to limit the inventive concepts claimed herein.

Referring now to the drawings, wherein like reference numerals designatelike or similar parts throughout the several views, there is illustratedin FIGS. 1–3 a conventional magnetic disk drive 30. Disk drive 30includes a spindle 32 that supports and rotates a magnetic disk 34.Spindle 32 is rotated by a motor 36 that, in turn, is controlled by amotor controller 38. A horizontal combined magnetic head 40 for readingand recording is mounted on a slider 42. Slider 42 is supported by asuspension 44 and actuator arm 46. A plurality of disks, sliders andsuspensions may be employed in a large capacity direct access storagedevice (DASD), as shown in FIG. 3. Suspension 44 and actuator arm 46position slider 42 to locate magnetic head 40 in a transducingrelationship with a surface of magnetic disk 34. When disk 34 is rotatedby motor 36, slider 42 is supported on a thin (typically, 0.05 μm)cushion of air (air bearing) between the disk and an air bearing surface(ABS) 48.

Magnetic head 40 may be employed for writing information to multiplecircular tracks on the surface of disk 34, as well as for readinginformation therefrom. Processing circuitry 50 exchanges signalsrepresenting such information with magnetic head 40, provides motordrive signals, and also provides control signals for moving slider 42 tovarious tracks. In FIGS. 1 and 4, slider 42 is shown mounted to a headgimbal assembly (HGA) 52 that is mounted to suspension 44. All of theabove components are supported on a base 53.

FIG. 5 is a side cross-sectional elevation view of a conventional mergedmagnetoresistive (MR) head 40 as viewed in plane V—V of FIG. 2. Magnetichead 40 has a write head portion 54 (“non-pedestal type”) and a readhead portion 56. The read head portion includes an MR sensor 58. MRsensor 58 is sandwiched between first and second gap layers 60 and 62that are, in turn, sandwiched between first and second shield layers 64and 66. In response to external magnetic fields, the resistance of MRsensor 58 changes. A sense current conducted through MR sensor 58 causesthese resistance changes to be manifested as potential changes, whichare processed by the processing circuitry 50 shown in FIG. 3.

Write head portion 54 of the head includes a coil layer 68 sandwichedbetween first and second insulation layers 70 and 72. First and secondinsulation layers 70 and 72 are referred to as an “insulation stack”.Coil layer 68 and first and second insulation layers 70 and 72 aresandwiched between first and second pole pieces 76 and 78. First andsecond pole pieces 76 and 78 are magnetically coupled at a back gap 80,and have first and second pole tips 82 and 84 that are separated by anon-magnetic gap layer 86 at the ABS. Note that coil layer 68 iscontained completely above non-magnetic gap layer 86 under and withinsecond pole piece 78. As shown in FIGS. 2 and 4, first and second solderconnections 88 and 90 connect leads (not shown) from MR sensor 58 toleads 96 and 98 on suspension 44; third and fourth solder connections100 and 102 connect leads 104 and 106 from write coil 68 (see FIG. 6) toleads 108 and 110 on suspension 44.

FIG. 8 is a partial cross-sectional view of another conventional sliderand magnetic head (“pedestal type”) as viewed in plane V—V of FIG. 2,where the magnetic head may include an MR or a GMR sensor. FIG. 9 is apartial ABS view of the slider taken along plane IX—IX of FIG. 8 to showread and write elements of this magnetic head. Although many componentsin this magnetic head are the same as those in FIG. 5, some differencesare apparent. For one, the head in FIG. 8 includes a pedestal-type writehead wherein first pole piece 76 includes a first pole piece layer 80and a plated pedestal 152. Pedestal 152 is formed on first pole piecelayer 80 by electroplating and is made of a magnetic material having ahigh magnetic moment. Non-magnetic gap layer 86 separates pedestal 152from second pole piece 78. Similar to pedestal 152, a back gap pedestal154 is formed on first pole piece layer 80 but in the back gap region. Athird pole piece 156, which is formed in an arcuate fashion with a frontend formed on top of second pole piece 78, serves as a magnetic fluxconnecting layer.

Conventional write coils 68 are formed within the magnetic head in adifferent manner than that in FIG. 5. In particular, a first layer ofcoil turns are formed below non-magnetic gap layer 86 in betweenpedestals 152 and 154 and a second layer of coil turns are formed abovesecond pole piece 78 within an arcuate spacing formed by third polepiece 156. Other differences from that in FIG. 5 are that shield layer66 and first pole piece layer 80 are not common layers; they areseparate. A non-magnetic separating layer 150 is formed between shieldlayer 66 and first pole piece layer 80.

Turning now to FIG. 10, a partial cross-sectional view of a magnetichead 1000 in accordance with one embodiment of the present invention isshown. A read head portion of magnetic head 1000 includes a GMR sensor1002 sandwiched in between first and second shield layers 1004 and 1006,being protected within surrounding insulator materials 1008. A writehead portion of magnetic head 1000 includes a magnetic yoke 1070.Magnetic yoke 1070 is the “horseshoe” or similarly shaped magnetic bodywhich has a lower magnetic pole and an upper magnetic pole. In theembodiment shown, the lower pole of magnetic yoke 1070 includes a firstpole piece layer 1012 and a first pedestal structure 1014 and the upperpole of magnetic yoke 1070 includes a second pole piece 1016 and a thirdpole piece layer 1028 which serves as a magnetic connecting layer to theback gap region.

First pedestal structure 1014 includes at least one pedestal, which maybe electroplated over first pole piece layer 1012 just behind an airbearing surface (ABS) 1020 of magnetic head 1000. In the embodimentshown, first pedestal structure 1014 is a double pedestal structurehaving an upper pedestal with a magnetic moment that is larger than thatof the lower pedestal. A non-magnetic write gap layer 1018 separates thepole tips of the lower and the upper poles, being particularly formedbetween first pedestal structure 1014 and second pole piece 1016. Thirdpole piece layer 1028 has a front end formed partially on top of secondpole piece 1016 and a back end formed on top of one or more magneticconnecting pedestals 1017 in the back gap region. The one or moremagnetic connecting pedestals 1017 are formed on top of first pole piecelayer 1012. A separation layer 1010 separates second shield layer 1006from first pole piece layer 1012.

Magnetic yoke 1070 may be made with any suitable magnetic materials,preferably materials having a high magnetic moment, such as variouscompositions of NiFe alloys, CoFe alloys, or FeAlN, with the inclusionof other common additives or dopants to control its material properties.Write gap layer 1018 and separation layer 1010 may be made of alumina(Al₂O₃) or other suitable non-magnetic or dielectric material.

During a write operation, magnetic write flux is produced across writegap layer 1018 across the pole tips of magnetic yoke 1070. Current isdriven through write coils 1022 to generate this magnetic write flux, asis conventional. As a result, heat is generated by write coils 1022 andthermally transferred to surrounding magnetic head components. Ifnothing is done to reduce such heating, thermal expansion willundesirably cause outward protrusion of pole tip materials from the ABS1020 and therefore the fly height of magnetic head 1000 will have to beincreased to avoid head-to-disk mechanical interaction.

According the present invention, write coils 1022 of magnetic head 1000are formed with a structure that reduces its electrical resistance tothereby reduce heating. This, in turn, reduces or substantiallyeliminates thermal protrusion at the ABS 1020.

As shown in FIG. 10, write coils 1022 are formed with a plurality ofcoil layers, such as a write coil layer 1024. Each coil layer 1024 ofwrite coils 1022 is made with an electrically conductive material, suchas copper (Cu). Other materials may be suitable, such as gold, silver,or aluminum. In between each coil layer 1024 is a dielectric coilseparating layer, such as a coil separating layer 1026, which may bemade from hard-baked photoresist, alumina (Al₂O₃), silicon-dioxide(SiO₂), or other suitable material.

As shown, each coil layer 1024 extends continuously between the lowerand upper poles of magnetic yoke 1070. One end of each coil layer 1024is in close proximity to a top of first pole piece layer 1012, beingseparated only by a thin insulative layer. The other end of each coillayer 1024 is in close proximity to a bottom of third pole piece layer1028 and is also separated by an insulator. It is noted that each coillayer 1024 even extends through a plane 1050 defined by write gap layer1018 (shown as a dashed line in FIG. 10).

As apparent, each coil layer 1024 of write coils 1022 is relativelytaller in height than those of conventional write coils. With suchconstruction, write coils 1022 utilize a large amount of electricallyconductive materials (e.g. copper) as compared to that used inconventional write coils. An increase in the volume of conductivematerials in write coils 1022 leads to a decrease in the electricalresistance of write coils 1022. A reduction in the electrical resistanceof write coils 1022 leads to a reduction of heat generation during thewrite process which, in turn, leads to a reduction in protrusion ofmagnetic head 1000.

The height (i.e. top to bottom) of each coil layer 1024 may be formedbetween about 2.0–7.0 micrometers (μm). In the present embodiment, theheight of each coil layer 1024 is about 4 μm. It is noted that, althoughmaximum benefits are provided where each coil layer 1024 extends betweenmagnetic yoke 1070 from top to bottom to the fullest practical extent,sufficient benefits may still be achieved with a reduced height of oneor both ends of each coil layer 1024. For example, one or both ends ofeach coil layer 1024 may extend to have a height that is at least halfthe height of its corresponding pole pedestal/structure.

As shown in FIG. 10, write coils 1022 are provided with six (6) coilturns. However, any suitable number of coil turns may be utilized. Forexample, write coils 1022 may have between about 1–20 coil turns. Forlower resistance coils, the width of coil layer 1024 should be maximizedwhile the width of coil separating layer 1026 should be minimized. Usingconventional coil fabrication processes, however, each coil separatinglayer 1026 can only be formed with a width of between 0.4–1.0 μm(nominally, 0.5 μm for a coil layer of 2 μm in height). On the otherhand, using techniques described herein, coil layer 1024 and coilseparating layer 1026 are formed such that each coil separating layer1026 can be made with a width of between about 0.2–0.3 μm (i.e. lessthan 0.4 μm). This can be done using a damascene process. Note that the“coil pitch” is the summation of coil layer 1024 and coil separatinglayer 1026.

As previously stated, write coils 1022 have a reduced electricalresistance which is sufficient to reduce thermal protrusion in magnetichead 1000. Conventional write coil structures with 6–7 coil turnstypically have resistances between about 4–9 Ohms (i.e. about 0.5–1.5Ohm per coil turn). Provided with the construction described above,write coils 1022 exhibit a relatively low electrical resistance of about2–4 Ohms. With 6–7 coil turns, this write coil structure provides about0.3–0.5 Ohms per coil turn. More generally, write coils 1022 of thepresent invention may exhibit electrical resistances of about 1–3 Ohms.With 6–7 coil turns, such a write coil structure provides about 0.15–0.5Ohms per coil turn. Advantageously, the structure can provide less than0.5 Ohms per coil turn and less than 4 Ohms of total electricalresistance.

Write coils 1022 may be formed in accordance with one of a number ofdifferent suitable techniques, conventional or otherwise. Preferably,write coils 1022 are fabricated utilizing a damascene process to achievea larger coil layer 1024 relative to each coil separating layer 1026. Ina damascene process, materials are formed (e.g. electroplated orvacuum-deposited) within openings previously made by etching (e.g. areactive ion etch or RIE), and excess material is removed by polishing(e.g. a chemical/mechanical polishing or CMP). The use of such a processallows the coil structures and the coil spaces to have a larger aspectratio (AR) and a smaller coil separating layer 1026 than write coils ofthe prior art.

Another source of heat in magnetic head 1000 is generated by eddycurrent losses during the write operation. To reduce such heating inmagnetic head 1000, either one or both of the lower and upper polesincludes a horizontally laminated structure of alternating magnetic andnon-magnetic dielectric layers. Such a laminated structure helps to“break up” and reduce such eddy current losses. To illustrate, FIG. 11is the same magnetic head shown in FIG. 10 except that the upper pole ofmagnetic yoke 1070 is made with a horizontally laminated structure 1102of alternating magnetic and non-magnetic dielectric layers. Horizontallylaminated structure 1102 may be formed on top of connecting magneticpedestals 1104 and 1106, which are formed on top of pole pieces 1016 and1017, respectively. FIG. 12 is the same magnetic head shown in FIG. 11except that the lower pole of magnetic yoke 1070 (i.e. the first polepiece layer) is also made with a horizontally laminated structure 1202of alternating magnetic and non-magnetic dielectric layers.

In FIGS. 11 and 12, each layer of the horizontally laminated structures1102 and 1202 may be vacuum-deposited and patterned by ion milling. Eachmagnetic layer may be made of the same magnetic materials previouslydescribed for magnetic yoke 1070, and each non-magnetic dielectric layermay be made of a suitable dielectric or non-magnetic material such asAlumina (Al₂O₃) or SiO₂. Each magnetic layer may have a thickness ofbetween about 50–2000 Angstroms and each non-magnetic dielectric layermay have a thickness of between about 10–200 Angstroms. In eachhorizontally-laminated structure, there may be a total of between 4–400layers of magnetic/non-magnetic dielectric materials.

Thus, the magnetic head described above includes a magnetic yoke; awrite gap layer formed between upper and lower poles of the magneticyoke; and a write coil having a plurality of coil layers. Each coillayer extends continuously between the upper and the lower poles througha plane defined by the write gap layer. The write coil is preferablyformed using a damascene process, where each coil layer has a largerwidth relative to each coil separating layer. Advantageously, the writecoil structure has a reduced electrical resistance for reducing theJoule heating produced in the write coils. Further, either one or bothof the lower and upper poles may include a horizontally laminatedstructure of alternating magnetic and non-magnetic dielectric layers tofurther reduce heating due to core losses originating from eddy currentlosses. The reduction of heating in the magnetic head leads to reducedprotrusion.

Turning now to FIG. 13, a partial cross-sectional view of a magnetichead 1300 in accordance with another embodiment of the present inventionis shown. A read head portion of magnetic head 1300 includes a GMRsensor 1302 sandwiched in between first and second shield layers 1304and 1306, being protected within surrounding insulator materials 1308. Awrite head portion of magnetic head 1300 includes a magnetic yoke 1370.Magnetic yoke 1370 is the “horseshoe” or similarly shaped magnetic bodywhich has a lower magnetic pole and an upper magnetic pole. In theembodiment shown, the lower pole of magnetic yoke 1370 includes a firstpole piece layer 1312 and a first pedestal structure 1314 and the upperpole of magnetic yoke 1370 includes a second pole piece 1316, a magneticconnecting pedestal 1350, and a third pole piece layer 1328 which servesas a magnetic connecting layer to the back gap region.

First pedestal structure 1314 includes at least one pedestal, which maybe electroplated over first pole piece layer 1312 just behind an airbearing surface (ABS) 1320 of magnetic head 1300. A non-magnetic writegap layer 1318 separates the pole tips of the lower and the upper poles,being formed particularly between first pedestal structure 1314 andsecond pole piece 1316. Third pole piece layer 1328 has a front endformed on top of magnetic connecting pedestal 1350, which is formed ontop of second pole piece 1316. Third pole piece layer 1328 has a backend formed on top of one or more magnetic connecting pedestals 1352 inthe back gap region. The one of more magnetic connecting pedestals 1352are formed on top of first pole piece layer 1312. A separation layer1310 separates second shield layer 1306 from first pole piece layer1312.

Magnetic yoke 1370 may be made with any suitable magnetic materials,preferably materials having a high magnetic moment, such as variouscompositions of NiFe alloys, CoFe alloys, or FeAlN, with the inclusionof other common additives or dopants to control its material properties.Write gap layer 1318 and separation layer 1310 may be made of alumina(Al₂O₃) or other suitable non-magnetic or dielectric material.

During a write operation, magnetic write flux is produced across writegap layer 1318 at the pole tips of magnetic yoke 1370. Current is driventhrough write coils 1322 to generate this magnetic write flux, as isconventional. As a result, heat is generated by write coils 1322 andthermally transferred to surrounding magnetic head components. Ifnothing is done to reduce such heating, thermal expansion willundesirably cause outward protrusion of pole tip materials from the ABS1320 and therefore the fly height will have to be increased to avoidheat-to-disk mechanical interaction.

According the present invention, write coils 1322 of magnetic head 1300are formed with a structure that reduces its electrical resistance tothereby reduce heating. This, in turn, reduces or eliminates protrusionof the head elements at the ABS 1320.

As shown in FIG. 13, write coils 1322 are formed with a plurality ofcoil layers, such as a write coil layer 1324. Each coil layer 1324 ofwrite coils 1322 is made with a suitable electrically conductivematerial, such as copper (Cu). Other materials may be suitable, such asgold, silver, and aluminum. In between each coil layer 1324 is aplurality of dielectric coil separating layers, such as a coilseparating layer 1326, which may be made from hard-baked photoresist,alumina (Al₂O₃), silicon-dioxide (SiO₂), or other suitable material.

As shown, each coil layer 1324 extends continuously between write gaplayer 1318 and the upper pole of magnetic yoke 1370. One end of eachcoil layer 1324 is in close proximity to a top of write gap layer 1318,being separated only by a thin insulative layer. The other end of eachcoil layer 1324 is in close proximity to a bottom of third pole piecelayer 1328 and is also separated by an insulator. It is noted that, inthis embodiment, no coil layer 1324 extends between the lower pole andwrite gap layer 1318.

As apparent, each coil layer 1324 of write coils 1322 is taller inheight than those of conventional write coils. Magnetic connectingpedestals 1350 and 1352 help to extend the height of each coil layer1324. With such construction, write coils 1322 utilize a relativelylarge amount of electrically conductive materials (e.g. copper) ascompared to that used in conventional write coils. An increase in thevolume of conductive materials in write coils 1322 leads to a decreasein the electrical resistance of write coils 1322. A reduction in theelectrical resistance of write coils 1322 leads to a reduction of heatgeneration during the write process which, in turn, leads to a reductionin protrusion of magnetic head 1300.

The height (i.e. top to bottom) of each coil layer 1324 may be formedbetween about 2.0–7.0 micrometers (μm). In the present embodiment, theheight of each coil layer 1324 is about 4 μm. It is noted that, althoughmaximum benefits are provided where each coil layer 1324 extends betweenmagnetic yoke 1370 from top to bottom to the fullest practical extent,sufficient benefits may be achieved with a reduced height of one or bothends of each coil layer 1324.

As shown in FIG. 13, write coils 1322 are provided with six (6) coilturns. However, any suitable number of coil turns may be provided. Forexample, write coils 1322 may preferably have between about 1–20 coilturns. For lower resistance coils, the width of coil layer 1324 shouldbe maximized while the width of coil separating layer 1326 should beminimized. Using conventional coil fabrication processes, however, eachcoil separating layer 1326 can only be formed with a width of between0.4–1.0 μm (nominally, 0.5 μm for a coil layer of 2 μm in height). Onthe other hand, using techniques described herein, coil layer 1324 andcoil separating layer 1326 are formed such that each coil separatinglayer 1326 can be made with a width of between about 0.2–0.3 μm (i.e.less than 0.4 μm). This can be achieved using a damascene process. Notethat the “coil pitch” is the summation of coil layer 1324 and coilseparating layer 1326.

As previously stated, write coils 1322 have a reduced electricalresistance which is sufficient to reduce thermal protrusion in magnetichead 1300. Conventional write coil structures with 6–7 coil turnstypically have resistances of between about 4–9 Ohms (i.e. about 0.5–1.5Ohm per coil turn). Provided with the construction described above,write coils 1322 exhibited a relatively low electrical resistance ofabout 2–4 Ohms.

With 6–7 coil turns, this write coil structure provides about 0.3–0.5Ohms per coil turn. More generally, write coils 1322 of the presentinvention may exhibit electrical resistances of about 1–3 Ohms. With 6–7coil turns, such a write coil structure provides about 0.15–0.5 Ohms percoil turn. Advantageously, the structure can provide less than 0.5 Ohmsper coil turn and less than 4 Ohms of total electrical resistance.

Write coils 1322 may be formed in accordance with one of a number ofdifferent suitable techniques, conventional or otherwise. Preferably,write coils 1322 are fabricated utilizing a damascene process to achievea larger width of each coil layer 1324 relative to each coil separatinglayer 1326. In a damascene process, materials are formed (e.g.electroplated or vacuum-deposited) within openings which are previouslyformed by etching (e.g. a reactive ion etch or RIE), and excess materialis removed by polishing (e.g. a chemical/mechanical polishing or CMP).The use of such a process allows the coil structures and the coil spacesto have a larger aspect ratio (AR) and a smaller coil separating spacethan write coils of the prior art.

Another source of heat in magnetic head 1300 is generated by eddycurrent losses during write operation. To reduce such heating inmagnetic head 1300, either one or both of the lower and upper polesincludes a horizontally laminated structure of alternating magnetic andnon-magnetic dielectric layers. Such a laminated structure helps to“break up” and reduce these eddy current losses. To illustrate, FIG. 14is the same magnetic head shown in FIG. 13 except that the upper pole ofmagnetic yoke 1370 is made with a horizontally laminated structure 1402of alternating magnetic and non-magnetic dielectric layers. Horizontallylaminated structure 1402 may be formed on top of magnetic connectingpedestals 1404 and 1406, which are formed on top of magnetic connectingpedestals 1350 and 1352, respectively. FIG. 15 is the same magnetic headshown in FIG. 14 except that the lower pole of magnetic yoke 1370 (i.e.the first pole piece layer) is also made with a horizontally laminatedstructure 1502 of alternating magnetic and non-magnetic dielectriclayers.

In FIGS. 14 and 15, each layer of the horizontally laminated structures1402 and 1502 may be formed by vacuum-deposition and subsequentpatterning by ion milling. Each magnetic layer may be made of the samemagnetic materials previously described for magnetic yoke 1370, and eachnon-magnetic dielectric layer may be made of a suitable dielectric ornon-magnetic material such as Alumina (Al₂O₃) or silicon-dioxide (SiO₂).Each magnetic layer may have a thickness of between about 50 and 2000Angstroms and each non-magnetic dielectric layer may have a thickness ofbetween about 10 and 200 Angstroms. In each horizontally-laminatedstructure, there may be a total of between 4 and 400 layers ofmagnetic/non-magnetic dielectric materials. Although shown in FIGS. 14and 15 to terminate at about the height of second pole piece 1350, thetop end of each coil layer 1324 may be further extended to be inclose/closer proximity to the bottom of horizontally laminated structure1402.

As apparent, the embodiments shown and described in relation to FIGS.13–15 may be preferred over that of FIGS. 10–12 where the spacingbetween the read sensor and the write gap layer are to be minimized andleft independent of the desired height of the write coils.

In even other embodiments, write coils 1322 and 1330 of FIGS. 13–15 arealternatively positioned in between write gap layer 1318 and the lowerpole of magnetic yoke 1370 (e.g. the first pole piece 1312). Here,additional magnetic connecting pedestals 1350 and 1352 are not formed inthe position shown in FIGS. 13–15, but rather are formed over first polepiece layer 1312. Thus, a magnetic head of the present invention may beconstructed such that the above-described write coils are positioned inbetween write gap layer and either the lower pole or the upper pole ofthe magnetic yoke.

Thus, a magnetic head as described above includes a magnetic yoke; awrite gap layer formed between upper and lower poles of the magneticyoke; and a write coil having a plurality of coil layers. Each coillayer extends continuously between the write gap layer and either thelower pole or the upper pole of the magnetic yoke. The write coil ispreferably formed using a damascene process, where each coil layer iswider than each coil separating layer. Advantageously, the write coilstructure has a reduced electrical resistance for reducing the Jouleheating produced in the write coils. Further, either one or both of thelower and upper poles may include a horizontally laminated structure ofalternating magnetic and non-magnetic dielectric layers to furtherreduce heating due to core losses originating from eddy current losses.The reduction of heating in the magnetic head leads to reducedprotrusion.

It is to be understood that the above is merely a description ofpreferred embodiments of the invention and that various changes,alterations, and variations may be made without departing from the truespirit and scope of the invention as set for in the appended claims. Fewif any of the terms or phrases in the specification and claims have beengiven any special meaning different from their plain language meaning,and therefore the specification is not to be used to define terms in anunduly narrow sense.

1. A magnetic head, comprising: a magnetic yoke; a write gap layerformed between upper and lower poles of the magnetic yoke; a pedestalformed above the lower pole; a pole piece formed below the upper pole; adamascene-constructed write coil having a plurality of coil layers; eachcoil layer of the damascene-constructed write coil extendingcontinuously between the upper and the lower poles through a planedefined by the write gap layer; and each coil layer extending from a topof one of the pedestal and the pole piece; to at least half of a heightof the other one of the pedestal and the pole piece.
 2. The magnetichead of claim 1, wherein the write coil has an electrical resistance ofless than 4 Ohms sufficient to reduce thermal protrusion at an airbearing surface (ABS) of the magnetic head.
 3. The magnetic head ofclaim 1, wherein the write coil has an electrical resistance that isless than 0.5 Ohms per coil turn.
 4. The magnetic head of claim 1,wherein each coil layer has a height between the upper and the lowerpoles that is 4 μm or greater.
 5. The magnetic head of claim 1, whereineach coil separating layer is less than 0.4 μm.
 6. The magnetic head ofclaim 1, wherein each coil layer extends from the top of the pole pieceto the bottom of the pedestal.
 7. The magnetic head of claim 1, furthercomprising: each coil layer further extending continuously to a fullestextent between the upper and lower and the lower poles.
 8. The magnetichead of claim 1, wherein each coil layer comprises copper and at leastone of the upper and lower poles further comprises: a pole piece layerover/under which the write coil is positioned; the pole piece layercomprising alternating layers of magnetic and non-magnetic dielectricmaterial.
 9. A magnetic recording device, comprising: at least onerotatable magnetic disk; a spindle supporting the at least one rotatablemagnetic disk; a disk drive motor for rotating the at least onerotatable magnetic disk; a magnetic head for writing data from the atleast one rotatable magnetic disk; a slider for supporting the magnetichead; the magnetic head including: a magnetic yoke; a write gap layerformed between upper and lower poles of the magnetic yoke; a pedestalformed above the lower pole; a pole piece formed below the upper pole; adamascene-constructed write coil having a plurality of coil layers; eachcoil layer of the damascene-construeted write coil extendingcontinuously between the upper and the lower poles through a planedefined by the write gap layer; and each coil layer extending from a topof one of the pedestal and the pole piece; to at least half of a heightof the other one of the pedestal and the pole piece.
 10. The magneticrecording device of claim 9, wherein the write coil has an electricalresistance of less than 4 Ohms sufficient to reduce thermal protrusionat an air bearing surface (ABS) of the magnetic head.
 11. The magneticrecording device of claim 9, wherein the write coil has an electricalresistance that is less than 0.5 Ohms per coil turn.
 12. The magneticrecording device of claim 9, wherein each coil layer has a heightbetween the upper and the lower poles that is 4 μm or greater.
 13. Themagnetic recording device of claim 9, wherein each coil separating layeris less than 0.4 μm.
 14. The magnetic recording device of claim 9,wherein each coil layer extends from the top of the pole piece to thebottom of the pedestal.
 15. The magnetic recording device of claim 9,further comprising: each coil layer further extending continuously to afullest extent between the upper and the lower poles.
 16. The magneticrecording device of claim 9, wherein at least one of the upper and lowerpoles further comprises: a pole piece layer over/under which the writecoil is positioned; the pole piece layer comprising alternating layersof magnetic and non-magnetic dielectric material.